Market share data for UK grocers underlines the slowdown in consumer spending, according to the TNS Worldpanel supermarket survey. The grocery market grew 3% in the 12 weeks ended August 12 - down from 6% in the 12 weeks to May 20. However, the big three - Tesco, Asda and Sainsbury's - all showed higher growth and have increased their market shares. They now have 65% of the grocery market, with Tesco accounting for 31.8%. Discounters Lidl and Aldi showed the fastest growth, with Somerfield lagging behind. Its market share has fallen from 4.4% to 3.9% in the past year.